Fixing preload (diy)
#1
Registered User
Thread Starter
iTrader: (15)
Join Date: Apr 2006
Location: Baltimore
Posts: 2,918
Likes: 0
Received 0 Likes
on
0 Posts
Fixing preload (diy)
I just installed some BC racing coilovers, and the fronts are on good and make no noises.
The rears are set all the way down, and when I had the Z in the air, the spring did not move up nor down, but you could turn it fairly easily.
I went for a testdrive, and every little bump I go over in the road, I can hear the rears making a thumping sound, so I know it's the preload.
Any idea on how to adjust/fix the preload? And perhaps where it should be at?
The rears are set all the way down, and when I had the Z in the air, the spring did not move up nor down, but you could turn it fairly easily.
I went for a testdrive, and every little bump I go over in the road, I can hear the rears making a thumping sound, so I know it's the preload.
Any idea on how to adjust/fix the preload? And perhaps where it should be at?
#2
Super Moderator
MY350Z.COM
MY350Z.COM
iTrader: (8)
I just installed some BC racing coilovers, and the fronts are on good and make no noises.
The rears are set all the way down, and when I had the Z in the air, the spring did not move up nor down, but you could turn it fairly easily.
I went for a testdrive, and every little bump I go over in the road, I can hear the rears making a thumping sound, so I know it's the preload.
Any idea on how to adjust/fix the preload? And perhaps where it should be at?
The rears are set all the way down, and when I had the Z in the air, the spring did not move up nor down, but you could turn it fairly easily.
I went for a testdrive, and every little bump I go over in the road, I can hear the rears making a thumping sound, so I know it's the preload.
Any idea on how to adjust/fix the preload? And perhaps where it should be at?
#4
Super Moderator
MY350Z.COM
MY350Z.COM
iTrader: (8)
First turn the rear up to around 20, your to low to run softer settings. Next take the rear shock and thread it in and make it slightly shorter. This should take care of your problem, if it not just the normal sounds that rear coilovers make on our cars.
Trending Topics
#8
Registered User
iTrader: (1)
Yes, I understand that about your springs. But is your shock/damper threaded all the way down also? If your springs are all the way down, the shock body itself has to be adjusted down too, to get the correct amount of piston travel. I also suggest stiffening up the dampers some too. Almost sounds like you have too little travel and are hitting the bump stops maybe?
#9
New Member
iTrader: (51)
I just installed some BC racing coilovers, and the fronts are on good and make no noises.
The rears are set all the way down, and when I had the Z in the air, the spring did not move up nor down, but you could turn it fairly easily.
I went for a testdrive, and every little bump I go over in the road, I can hear the rears making a thumping sound, so I know it's the preload.
Any idea on how to adjust/fix the preload? And perhaps where it should be at?
The rears are set all the way down, and when I had the Z in the air, the spring did not move up nor down, but you could turn it fairly easily.
I went for a testdrive, and every little bump I go over in the road, I can hear the rears making a thumping sound, so I know it's the preload.
Any idea on how to adjust/fix the preload? And perhaps where it should be at?
#11
Former Sponsor
iTrader: (564)
Join Date: Feb 2003
Location: Long Island, New York
Posts: 19,266
Likes: 0
Received 5 Likes
on
5 Posts
preload is adjusted by threading the collar that holds the spring. Whatever change you make to the spring, you should also then translate and make to the damper.
To the OP, I doubt preload is your issue - sounds like you left something loose such as the center nut on the damper itself, etc
#12
Registered User
iTrader: (2)
Join Date: Jun 2007
Location: Scotland
Posts: 204
Likes: 0
Received 0 Likes
on
0 Posts
simple - on springs that use OEM spring locations, the spring itself will sit on a threaded collar, and so will the shock, or damper, itself\
preload is adjusted by threading the collar that holds the spring. Whatever change you make to the spring, you should also then translate and make to the damper.
To the OP, I doubt preload is your issue - sounds like you left something loose such as the center nut on the damper itself, etc
preload is adjusted by threading the collar that holds the spring. Whatever change you make to the spring, you should also then translate and make to the damper.
To the OP, I doubt preload is your issue - sounds like you left something loose such as the center nut on the damper itself, etc
#13
Former Sponsor
iTrader: (564)
Join Date: Feb 2003
Location: Long Island, New York
Posts: 19,266
Likes: 0
Received 5 Likes
on
5 Posts
Colin - not sure what you are trying to accomplish? Preload should be set to a minimal amount, where the spring is not able to wiggle around - basically so that it is secure in its perch and not able to be moved up and down when the car is in the air (suspension unloaded). From there, you really only should be altering preload via corner balanacing, with the car on scales.
#14
Registered User
iTrader: (2)
Join Date: Jun 2007
Location: Scotland
Posts: 204
Likes: 0
Received 0 Likes
on
0 Posts
Colin - not sure what you are trying to accomplish? Preload should be set to a minimal amount, where the spring is not able to wiggle around - basically so that it is secure in its perch and not able to be moved up and down when the car is in the air (suspension unloaded). From there, you really only should be altering preload via corner balanacing, with the car on scales.
#15
Registered User
iTrader: (5)
Join Date: Aug 2006
Location: NJ
Posts: 66
Likes: 0
Received 0 Likes
on
0 Posts
When I spoke to Pete from BC, this is how he explained adjusting the rear springs and dampers.
1. You have to remove the lower mounting bolt from the dampers so it's disconnected from the rear suspension arm.
2. Assuming the springs are set to desired ride height use a jack and raise the lower suspension arm up 1/4" from this point, this sets the location for where to line up the lower shock mount.
3. Now thread the shock body up or down as needed to line up with the hole. Tighten up the lower lock ring.
Hope this helps.
1. You have to remove the lower mounting bolt from the dampers so it's disconnected from the rear suspension arm.
2. Assuming the springs are set to desired ride height use a jack and raise the lower suspension arm up 1/4" from this point, this sets the location for where to line up the lower shock mount.
3. Now thread the shock body up or down as needed to line up with the hole. Tighten up the lower lock ring.
Hope this helps.
#16
Registered User
Thread Starter
iTrader: (15)
Join Date: Apr 2006
Location: Baltimore
Posts: 2,918
Likes: 0
Received 0 Likes
on
0 Posts
Ah, something I clearly overlooked when putting the rears on.
When I put them on, I left them from the previous owners settings.
Then, when I put the rear springs all the way down, I forgot to adjust the shock all the way down as well. AH!
Well, I just finished adjusting it, and the spring is crazy snug now, under load and under no load.
Well, I went for a test run, and wouldn't you know, the sound went away slightly, but it still makes a thumping sound when I go over bumps/etc.
I took a small vid just to describe the sound to see if that helps,
You can hear a "thump" sound at 8 second and then again at 2 and 1 seconds left.
I tripled checked every loose thing, and found nothing out of place...gr, this is bothering me...
When I put them on, I left them from the previous owners settings.
Then, when I put the rear springs all the way down, I forgot to adjust the shock all the way down as well. AH!
Well, I just finished adjusting it, and the spring is crazy snug now, under load and under no load.
Well, I went for a test run, and wouldn't you know, the sound went away slightly, but it still makes a thumping sound when I go over bumps/etc.
I took a small vid just to describe the sound to see if that helps,
You can hear a "thump" sound at 8 second and then again at 2 and 1 seconds left.
I tripled checked every loose thing, and found nothing out of place...gr, this is bothering me...
#19
Former Sponsor
iTrader: (564)
Join Date: Feb 2003
Location: Long Island, New York
Posts: 19,266
Likes: 0
Received 5 Likes
on
5 Posts
I can ask the guys at BC tomorrow morning, but if I had to give my best estimate, 50-65 ft lbs is typical for coilovers for that center nut
also while you're there just check to make sure there is no slop at the rear upper bearing in the mount - I've never heard/seen of one going bad, but mind as well check while you're there
also while you're there just check to make sure there is no slop at the rear upper bearing in the mount - I've never heard/seen of one going bad, but mind as well check while you're there